During module design planning of a chip comprising a test chain, arbitrary distribution of the scan components will cause too many connection wires to be present between various planned units. Meanwhile, each planned unit also needs to create more terminals for input and output of scan signals. As a result, each planned unit has a very large demand for resources during application at the top level, thus enhancing the difficulty in design. In order to reduce the number of ports on the planned units and connection wires between the units caused by the scan chain going through the planned unit, it is necessary to reconfigure the scan chain, that is, to adjust the position of the scan components to form a new scan chain.
FIG. 1 is a reconfiguration method of a scan chain: First in Step 70, the starting point of said scan chain serves as a reference component, and in Step 71, the distance of said reference component to all other available scan components in said scan chain is calculated, to determine the scan component closest to it; in Step 72, said reference component and said scan component closest to it are connected; in Step 73, said scan component closest to it serves as a reference component; and in Step 74, if said reference component is the last available scan component is checked; if yes, then in Step 75 it is connected to the ending point of the scan chain; otherwise, the process goes back to Step 71.
Said reconfiguration method for scan chains only considers the relationship between scan components in terms of distance, without considering information of the position of the planned unit where each scan component is located, so while the length of the scan chain acquired is shortened, it may go through even more planned units than before reconfiguration, thus resulting in the existence of too many connection wires among planned units. Even though after re-arrangement, the number of ports on the planned units and connection wires between planned units is somewhat reduced, there is still room to further reduce the number of ports and connection wires through reconfiguration of the scan chain.
In view of this, the industry still needs a technical plan of reconfiguration of scan chains to solve the problem of too many ports on the planned units and too many connection wires between planned units.